Hi.
The most recent ISO posted to my.vmware.com for the Cisco OEM ESXi 7.0U2 ISO is from April 2021. I believe that if you've been keeping up with security patches on ESXi 6.7, the April 7.x ISO is considered an incompatible upgrade image due to the back-in-time restrictions on ESXi upgrades.
Does Cisco plan to release an updated OEM ISO that would include the most recent set of patches?